I carry it, have never used it, but I don't want to be the one guy who perhaps needed it just one time. I hike alone and it does give me a bit of "comfort."
I used to live in Maine and have seen many bear while out on a trail or just walking along a dirt road, but since moving to Washington State I've had more "problems" with the dam mountain goats in the Olympics. Not serious trouble, but they are ornery and have a bit of history.